TypeScript 4.0: Support labeled tuple elements

packages/babel-parser/src/plugins/typescript/index.js

@@ -76,6 +76,8 @@ const TSErrors = Object.freeze({
   IndexSignatureHasStatic: "Index signatures cannot have the 'static' modifier",
   OptionalTypeBeforeRequired:
     "A required element cannot follow an optional element.",
+  MixedLabeledAndUnlabeledElements:
+    "Tuple members must all have names or all not have names.",
   PatternIsOptional:
     "A binding pattern parameter cannot be optional in an implementation signature.",
   PrivateElementHasAbstract:
@@ -633,12 +635,44 @@ export default (superClass: Class<Parser>): Class<Parser> =>
       // Validate the elementTypes to ensure that no mandatory elements
       // follow optional elements
       let seenOptionalElement = false;
+      let labeledElements = null;
       node.elementTypes.forEach(elementNode => {
-        if (elementNode.type === "TSOptionalType") {
-          seenOptionalElement = true;
-        } else if (seenOptionalElement && elementNode.type !== "TSRestType") {
+        const { type } = elementNode;
+
+        if (
+          seenOptionalElement &&
+          type !== "TSRestType" &&
+          type !== "TSOptionalType" &&
+          !(type === "TSNamedTupleMember" && elementNode.optional)
+        ) {
           this.raise(elementNode.start, TSErrors.OptionalTypeBeforeRequired);
         }
+
+        // Flow doesn't support ||=
+        seenOptionalElement =
+          seenOptionalElement ||
+          (type === "TSNamedTupleMember" && elementNode.optional) ||
+          type === "TSOptionalType";
+
+        // Don't check labels on spread elements
+        if (type === "TSRestType") return;
+
+        const isLabeled = type === "TSNamedTupleMember";
+
+        if (labeledElements === false && isLabeled) {
+          this.raise(
+            elementNode.start,
+            TSErrors.MixedLabeledAndUnlabeledElements,
+          );
+        } else if (labeledElements === true && !isLabeled) {
+          this.raise(
+            elementNode.start,
+            TSErrors.MixedLabeledAndUnlabeledElements,
+          );
+        }
+
+        // Flow doesn't support ??=
+        labeledElements = labeledElements ?? isLabeled;
       });
 
       return this.finishNode(node, "TSTupleType");
@@ -654,12 +688,29 @@ export default (superClass: Class<Parser>): Class<Parser> =>
       }
 
       const type = this.tsParseType();
+
+      const maybeLabeledElement =
+        type.type === "TSTypeReference" &&
+        !type.typeParameters &&
+        type.typeName.type === "Identifier";
+
+      const optional = this.eat(tt.question);
+
+      if (maybeLabeledElement && this.eat(tt.colon)) {
+        const labeledNode: N.TsNamedTupleMember = this.startNodeAtNode(type);
+        labeledNode.optional = optional;
+        labeledNode.label = type.typeName;
+        labeledNode.elementType = this.tsParseType();
+        return this.finishNode(labeledNode, "TSNamedTupleMember");
+      }
+
       // parses `TsType?`
-      if (this.eat(tt.question)) {
+      if (optional) {
         const optionalTypeNode: N.TsOptionalType = this.startNodeAtNode(type);
         optionalTypeNode.typeAnnotation = type;
         return this.finishNode(optionalTypeNode, "TSOptionalType");
       }
+
       return type;
     }
 

packages/babel-parser/src/types.js

@@ -1264,7 +1264,14 @@ export type TsArrayType = TsTypeBase & {
 
 export type TsTupleType = TsTypeBase & {
   type: "TSTupleType",
-  elementTypes: $ReadOnlyArray<TsType>,
+  elementTypes: $ReadOnlyArray<TsType | TsTupleElementType>,
+};
+
+export type TsNamedTupleMember = TsTypeBase & {
+  type: "TSNamedTupleMember",
+  label: Identifier,
+  optional: boolean,
+  elementType: TsType,
 };
 
 export type TsOptionalType = TsTypeBase & {

packages/babel-parser/test/fixtures/typescript/types/tuple-invalid-label-1/input.ts

@@ -0,0 +1 @@
+type T = [x.y: A];

packages/babel-parser/test/fixtures/typescript/types/tuple-invalid-label-1/options.json

@@ -0,0 +1,7 @@
+{
+  "sourceType": "module",
+  "plugins": [
+    "typescript"
+  ],
+  "throws": "Unexpected token, expected \",\" (1:13)"
+}

packages/babel-parser/test/fixtures/typescript/types/tuple-invalid-label-2/input.ts

@@ -0,0 +1 @@
+type T = [x<y>: A];

packages/babel-parser/test/fixtures/typescript/types/tuple-invalid-label-2/options.json

@@ -0,0 +1,7 @@
+{
+  "sourceType": "module",
+  "plugins": [
+    "typescript"
+  ],
+  "throws": "Unexpected token, expected \",\" (1:14)"
+}

packages/babel-parser/test/fixtures/typescript/types/tuple-labeled-after-unlabeled/input.ts

@@ -0,0 +1 @@
+type T = [A, y: B];

packages/babel-parser/test/fixtures/typescript/types/tuple-labeled-after-unlabeled/output.json

@@ -0,0 +1,59 @@
+{
+  "type": "File",
+  "start":0,"end":19,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":19}},
+  "errors": [
+    "SyntaxError: Tuple members must all have names or all not have names. (1:13)"
+  ],
+  "program": {
+    "type": "Program",
+    "start":0,"end":19,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":19}},
+    "sourceType": "module",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "TSTypeAliasDeclaration",
+        "start":0,"end":19,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":19}},
+        "id": {
+          "type": "Identifier",
+          "start":5,"end":6,"loc":{"start":{"line":1,"column":5},"end":{"line":1,"column":6},"identifierName":"T"},
+          "name": "T"
+        },
+        "typeAnnotation": {
+          "type": "TSTupleType",
+          "start":9,"end":18,"loc":{"start":{"line":1,"column":9},"end":{"line":1,"column":18}},
+          "elementTypes": [
+            {
+              "type": "TSTypeReference",
+              "start":10,"end":11,"loc":{"start":{"line":1,"column":10},"end":{"line":1,"column":11}},
+              "typeName": {
+                "type": "Identifier",
+                "start":10,"end":11,"loc":{"start":{"line":1,"column":10},"end":{"line":1,"column":11},"identifierName":"A"},
+                "name": "A"
+              }
+            },
+            {
+              "type": "TSNamedTupleMember",
+              "start":13,"end":17,"loc":{"start":{"line":1,"column":13},"end":{"line":1,"column":17}},
+              "optional": false,
+              "label": {
+                "type": "Identifier",
+                "start":13,"end":14,"loc":{"start":{"line":1,"column":13},"end":{"line":1,"column":14},"identifierName":"y"},
+                "name": "y"
+              },
+              "elementType": {
+                "type": "TSTypeReference",
+                "start":16,"end":17,"loc":{"start":{"line":1,"column":16},"end":{"line":1,"column":17}},
+                "typeName": {
+                  "type": "Identifier",
+                  "start":16,"end":17,"loc":{"start":{"line":1,"column":16},"end":{"line":1,"column":17},"identifierName":"B"},
+                  "name": "B"
+                }
+              }
+            }
+          ]
+        }
+      }
+    ],
+    "directives": []
+  }
+}

packages/babel-parser/test/fixtures/typescript/types/tuple-labeled-before-unlabeled/input.ts

@@ -0,0 +1 @@
+type T = [x: A, B];

packages/babel-parser/test/fixtures/typescript/types/tuple-labeled-before-unlabeled/output.json

@@ -0,0 +1,59 @@
+{
+  "type": "File",
+  "start":0,"end":19,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":19}},
+  "errors": [
+    "SyntaxError: Tuple members must all have names or all not have names. (1:16)"
+  ],
+  "program": {
+    "type": "Program",
+    "start":0,"end":19,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":19}},
+    "sourceType": "module",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "TSTypeAliasDeclaration",
+        "start":0,"end":19,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":19}},
+        "id": {
+          "type": "Identifier",
+          "start":5,"end":6,"loc":{"start":{"line":1,"column":5},"end":{"line":1,"column":6},"identifierName":"T"},
+          "name": "T"
+        },
+        "typeAnnotation": {
+          "type": "TSTupleType",
+          "start":9,"end":18,"loc":{"start":{"line":1,"column":9},"end":{"line":1,"column":18}},
+          "elementTypes": [
+            {
+              "type": "TSNamedTupleMember",
+              "start":10,"end":14,"loc":{"start":{"line":1,"column":10},"end":{"line":1,"column":14}},
+              "optional": false,
+              "label": {
+                "type": "Identifier",
+                "start":10,"end":11,"loc":{"start":{"line":1,"column":10},"end":{"line":1,"column":11},"identifierName":"x"},
+                "name": "x"
+              },
+              "elementType": {
+                "type": "TSTypeReference",
+                "start":13,"end":14,"loc":{"start":{"line":1,"column":13},"end":{"line":1,"column":14}},
+                "typeName": {
+                  "type": "Identifier",
+                  "start":13,"end":14,"loc":{"start":{"line":1,"column":13},"end":{"line":1,"column":14},"identifierName":"A"},
+                  "name": "A"
+                }
+              }
+            },
+            {
+              "type": "TSTypeReference",
+              "start":16,"end":17,"loc":{"start":{"line":1,"column":16},"end":{"line":1,"column":17}},
+              "typeName": {
+                "type": "Identifier",
+                "start":16,"end":17,"loc":{"start":{"line":1,"column":16},"end":{"line":1,"column":17},"identifierName":"B"},
+                "name": "B"
+              }
+            }
+          ]
+        }
+      }
+    ],
+    "directives": []
+  }
+}

packages/babel-parser/test/fixtures/typescript/types/tuple-labeled-invalid-optional/input.ts

@@ -0,0 +1 @@
+type T = [x: A?];

packages/babel-parser/test/fixtures/typescript/types/tuple-labeled-invalid-optional/options.json

@@ -0,0 +1,7 @@
+{
+  "sourceType": "module",
+  "plugins": [
+    "typescript"
+  ],
+  "throws": "Unexpected token, expected \",\" (1:14)"
+}

packages/babel-parser/test/fixtures/typescript/types/tuple-labeled/input.ts

@@ -0,0 +1 @@
+type T = [foo: string, bar?: number];

packages/babel-parser/test/fixtures/typescript/types/tuple-labeled/output.json

@@ -0,0 +1,56 @@
+{
+  "type": "File",
+  "start":0,"end":37,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":37}},
+  "program": {
+    "type": "Program",
+    "start":0,"end":37,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":37}},
+    "sourceType": "module",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "TSTypeAliasDeclaration",
+        "start":0,"end":37,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":37}},
+        "id": {
+          "type": "Identifier",
+          "start":5,"end":6,"loc":{"start":{"line":1,"column":5},"end":{"line":1,"column":6},"identifierName":"T"},
+          "name": "T"
+        },
+        "typeAnnotation": {
+          "type": "TSTupleType",
+          "start":9,"end":36,"loc":{"start":{"line":1,"column":9},"end":{"line":1,"column":36}},
+          "elementTypes": [
+            {
+              "type": "TSNamedTupleMember",
+              "start":10,"end":21,"loc":{"start":{"line":1,"column":10},"end":{"line":1,"column":21}},
+              "optional": false,
+              "label": {
+                "type": "Identifier",
+                "start":10,"end":13,"loc":{"start":{"line":1,"column":10},"end":{"line":1,"column":13},"identifierName":"foo"},
+                "name": "foo"
+              },
+              "elementType": {
+                "type": "TSStringKeyword",
+                "start":15,"end":21,"loc":{"start":{"line":1,"column":15},"end":{"line":1,"column":21}}
+              }
+            },
+            {
+              "type": "TSNamedTupleMember",
+              "start":23,"end":35,"loc":{"start":{"line":1,"column":23},"end":{"line":1,"column":35}},
+              "optional": true,
+              "label": {
+                "type": "Identifier",
+                "start":23,"end":26,"loc":{"start":{"line":1,"column":23},"end":{"line":1,"column":26},"identifierName":"bar"},
+                "name": "bar"
+              },
+              "elementType": {
+                "type": "TSNumberKeyword",
+                "start":29,"end":35,"loc":{"start":{"line":1,"column":29},"end":{"line":1,"column":35}}
+              }
+            }
+          ]
+        }
+      }
+    ],
+    "directives": []
+  }
+}

packages/babel-parser/test/fixtures/typescript/types/tuple-required-after-labeled-optional/input.ts

@@ -0,0 +1 @@
+type T = [x?: A, y: B];

packages/babel-parser/test/fixtures/typescript/types/tuple-required-after-labeled-optional/output.json

@@ -0,0 +1,69 @@
+{
+  "type": "File",
+  "start":0,"end":23,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":23}},
+  "errors": [
+    "SyntaxError: A required element cannot follow an optional element. (1:17)"
+  ],
+  "program": {
+    "type": "Program",
+    "start":0,"end":23,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":23}},
+    "sourceType": "module",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "TSTypeAliasDeclaration",
+        "start":0,"end":23,"loc":{"start":{"line":1,"column":0},"end":{"line":1,"column":23}},
+        "id": {
+          "type": "Identifier",
+          "start":5,"end":6,"loc":{"start":{"line":1,"column":5},"end":{"line":1,"column":6},"identifierName":"T"},
+          "name": "T"
+        },
+        "typeAnnotation": {
+          "type": "TSTupleType",
+          "start":9,"end":22,"loc":{"start":{"line":1,"column":9},"end":{"line":1,"column":22}},
+          "elementTypes": [
+            {
+              "type": "TSNamedTupleMember",
+              "start":10,"end":15,"loc":{"start":{"line":1,"column":10},"end":{"line":1,"column":15}},
+              "optional": true,
+              "label": {
+                "type": "Identifier",
+                "start":10,"end":11,"loc":{"start":{"line":1,"column":10},"end":{"line":1,"column":11},"identifierName":"x"},
+                "name": "x"
+              },
+              "elementType": {
+                "type": "TSTypeReference",
+                "start":14,"end":15,"loc":{"start":{"line":1,"column":14},"end":{"line":1,"column":15}},
+                "typeName": {
+                  "type": "Identifier",
+                  "start":14,"end":15,"loc":{"start":{"line":1,"column":14},"end":{"line":1,"column":15},"identifierName":"A"},
+                  "name": "A"
+                }
+              }
+            },
+            {
+              "type": "TSNamedTupleMember",
+              "start":17,"end":21,"loc":{"start":{"line":1,"column":17},"end":{"line":1,"column":21}},
+              "optional": false,
+              "label": {
+                "type": "Identifier",
+                "start":17,"end":18,"loc":{"start":{"line":1,"column":17},"end":{"line":1,"column":18},"identifierName":"y"},
+                "name": "y"
+              },
+              "elementType": {
+                "type": "TSTypeReference",
+                "start":20,"end":21,"loc":{"start":{"line":1,"column":20},"end":{"line":1,"column":21}},
+                "typeName": {
+                  "type": "Identifier",
+                  "start":20,"end":21,"loc":{"start":{"line":1,"column":20},"end":{"line":1,"column":21},"identifierName":"B"},
+                  "name": "B"
+                }
+              }
+            }
+          ]
+        }
+      }
+    ],
+    "directives": []
+  }
+}

packages/babel-parser/test/fixtures/typescript/types/tuple-spread-after-labeled/input.ts

@@ -0,0 +1 @@
+type T = [x: A, ...B];